Cooper Tire Discoverer AT3 & S/TMaxx Tire Test

Cooper Tire Discoverer AT3 Mud Test

We were off to the mud. Cooper has taken roughly an acre of land and installed agricultural sprinklers so they can create and control a field of mud. They control its depth and consistency. We tested two Cherokee’s one outfitted with the ST’s and the other outfitted with the AT3’s. The mud field allowed us to drive through varying consistencies of mud, stopping and starting the trucks to see if they would get you out of trouble.

Riding Shotgun with Johnny Unser

by Perry Mack

This is footage of myself riding shotgun with Johnny Unser at the Cooper Tire test Centre outside of San Antonio, Texas in a Mustang GT. A couple of interesting things to notice is that although I look quite calm with Johnny cranking out clouds of blue smoke with the Cooper Zeon RS3 tires screaming in the background; inside my butt cheeks are clenched wondering when we're going to careen off the track tumbling through the Texas desert like a burning sagebrush in a hurricane at 120 kph.

If you watch closely at the beginning of the video you'll see a Mickey Thompson Baja race truck starting out on the 5 km test track through the desert. Roaring through this 1,000 acre test facility on washed out dirt roads, stream beds and raw desert, buring the needle at over 160 kph on a set of Cooper Discoverer AT3's. On that shotgun test drive my butt cheeks just about let go.

If you see either of these two vehicles come up for sale used, walk away, just walk away.

This wasn’t your average Q & A with Johnny Unser (of the Bobby Sr, Bobby Jr and Al Unser family). I asked the questions, Johnny calmly and casually answered the questions – while we were drifting through corners at 60 mph. The helmet I was wearing made it a little hard to hear, as did the tires, screeching through hairpin turns, chicanes and figure 8’s. As we passed through the clouds of blue smoke and the smell of exhaust and burning rubber on our way to the second lap, Johnny turned to me and said “Ready? The tires should be good and warmed up now.” My ass was puckered up tight.

We were at the Cooper Tire Test Centre in San Antonio, TX where Cooper tire was attempting to convince the off-road media that their new All Terrain Tire was truly all terrain. As most Canadians know, an ‘all-season’ tire is really a three season tire. So when we hear the word ‘all’ used to describe a tire we’re naturally suspicious.

And rightly so, because we know that if the tire doesn’t perform, it doesn’t matter how much you spent on your truck, you won’t get your monies worth. It’s easy to argue that choosing the right tire and maintaining your tires are a couple of the most important decisions about your vehicle you make. Tires influence your gas mileage, your ability to turn and stop, and of course whether or not you can move at all, given the type of terrain you’re attempting to traverse.

Most tire designers will acknowledge that engineering tires is a process of compromises. Increase rubber grip and you sacrifice durability, increase siping and you lose traction on dry pavement (the size of the contact patch decreases) and the list continues. Suffice to say that the evolution of tire design is about continually improving a tires handling, durability, ride and traction while making fewer comprises. We take these small evolutionary advances for granted but keep in mind that sometimes they evolve into major milestones like the development of the pneumatic tire (which we all drive on today) and the radial tire.

Which brings me to the Cooper Tire Test Centre today. Cooper wants to prove they have the most advanced all-terrain tire on the market and it’s not the most expensive. It’s a wet track, head to head test against the BF Goodrich All Terrain T/A KO and then a hands on demonstration in the mud, hill climbs and rock climbs using I drove a variety of Cherokees, Wranglers and Wrangler Unlimited’s. None of the vehicles had any performance off-road upgrades – we drove Sahara’s not Rubicon’s, nothing equipped with lockers.

Cooper Tire laid out an obstacle course on their wet track. First we drove a Tahoe equipped with BF Goodrich tires through three timed laps of the course. The course is designed to test the acceleration, traction through a turn and traction while braking and loading the tire in a turn. I consider the last one the most important. When a tire fails here, accidents happen. The Cooper AT3 tire is designed for those of us who drive our vehicles off-road and also use it as our daily driver. We’re not going to intentionally push the limits of the tire on wet pavement through hard decelerations. But to avoid an accident, odds are we will have to brake hard and turn sharp.

The BF’s drove like typical all-terrain tires do on wet pavement. You can virtually hear and feel the outside lugs losing traction as you brake and turn. I can mentally imagine the sound of breaking glass and bending metal as I push the tire and it loses traction, sending cones flying and crunching under the truck.

In comparison the AT3’s held their traction longer. On average the test drivers completed the course roughly 10% faster on the AT3’s . Qualitatively, I felt much more confident on the AT3’s right from the first turn, from the sound of tires to the feel through the steering wheel.

While other drivers took turns through the wet track I had a chance to speak with Ali Ajibouri one of Cooper Tires key tire advisors. I commented that the off-road obstacles I’d seen weren’t particularly impressive. Ali calmly replied, “The Test Centre was never intended to provide hours of off-roading entertainment. The goal was to build a facility in which we could test the performance and durability of different tire designs”. At that point he buried the needle in the Mickey Thompson off-road racer and we were somewhere south of 180 kph over a washed out, gravel creek bed. I was puckered tight again, whooping it up as Ali drifted through high-speed corners over the 3-mile desert course. Do these guys ever conduct a normal interview? The truck was running on Discover AT3’s.

We were off to the mud. Cooper has taken roughly an acre of land and installed agricultural sprinklers so they can create and control a field of mud. They control its depth and consistency. We tested two Cherokee’s one outfitted with the ST’s and the other outfitted with the AT3’s. The mud field allowed us to drive through varying consistencies of mud, stopping and starting the trucks to see if they would get you out of trouble. Taking the truck as fast as possible through the mud is easy – not much of a test. Our off-road trucks are often work trucks as much as fun wheelin’ vehicles. We drive through muddy construction sites, orchards and ranchlands. You don’t always know when you’ll find mud and you don’t always know when you’ll have to stop and start in it.

I expected the S/TMaxx’s to be great and they were – that’s their job. Starting, stopping and driving through the wet sloppy soup and heavy, sticky muck was effortless. The surprising part is that the AT3’s were virtually as good, in fact I doubt if most of the other drivers could even tell the difference. There were no issues driving in axle deep mud.

We were off to the ‘hill’ climbs. Where the mud is designed to test the treads ability to provide traction these ramps are designed to test the rubber as well. As Ali admitted earlier, they’re not designed to provide hours of entertainment but they will test a tires ability to climb. The man-made hill provided three types of unnatural terrain, smooth wet concrete – so slick you couldn’t walk up it safely, concrete embedded with wet rock and rough wet concrete. Even the most inexperienced drivers effortlessly drove up the slick wet concrete ramp. The rubber certainly does its job. The embedded stones provided a little more entertainment. The stones tested not only the rubbers’ ability to grip, but also the tires ability to deform and gain traction with a reduced contact patch. Here a number of the other drivers got stuck (from the traditional American automotive media not the 4WD guys) and had to drive down backwards and start again.

By now the afternoon temperatures were approaching 40 degrees Celsius and tiny black flies were taking chunks off me like I was meat at a Brazilian steak house. Our next stop was the rock crawl section and the V-Notch. I didn’t get to drive the rock crawl course so I can’t comment on how the tire performed vs. other tires but watching from the sidelines, they did get Ali through effortlessly.

The V-notch would have been a really boring drive, but that’s ok, its purpose isn’t to entertain, its purpose is to destroy. The V-notch, similar to the crawl but in a more extreme way, tests the tires durability. How badly will the tread get cut up on sharp rocks, how will the sidewall stand up when the it has to hold the weight of the truck. Up close and personal with the V-notch the AT3’s looked good.

The last obstacle was a muck pool with a slick rock climb out. Here Cooper is simulating a real world obstacle. You go down into a creek and have to climb out the other side. They add water to a ditch and let it stagnate so it has a good growth of bacteria and slime. Just like real life it greases the tire in an organic ooze. After the first few trucks had been through and stirred up the muck, the smell was real-life cesspool - backed up septic field nauseating. I drove the Wrangler down, through and out effortlessly. Organic slime and all, the tires performed perfectly. Not so for a few of the inexperienced drivers who picked bad lines and didn’t listen to their spotter. They got stuck, dinged bumpers, scraped bottoms until finally a muffler was ripped off. It’s not a trail ride until you break something.

From there it was a 15-minute trail ride back to the main building. I got a good chuckle from the driver who stuck his Wrangler Unlimited on a sharp hump, all four tires spinning uselessly in the air. Now he knows for certain that it does have a longer wheelbase.

However one terrain important to Canadians that wasn’t tested, was snow. According to Ali, snow traction in the AT3 is excellent but I couldn’t test this in the desert. For many of us in different parts of the country, early and late season trail rides include (often unexpected) snow conditions. And I for one don’t always get my snow tires on in time. The AT3 doesn’t have and won’t get the mountain/snowflake logo. For drivers in Quebec, this means you’ll still need to buy a set of winters to comply with Law 42 and for drivers in British Columbia there are some mountain highways you won’t be allowed to drive.

I ordered a set from Cooper for my Dodge Ram 1500 and went up into the mountains. Although the AT3’s are not a snow tire they did perform well enough in the late season wet snow I found as well as the following mud. After abusing these tires on wet pavement, mud, rock, ooze and snow – with jeeps and a half-ton pick-up, I can honestly say they are a true all-terrain tire and the best I’ve tested.